Hardness sensing rotary cutters for mineral mining machines



u nlteu States l'atent m nna WW999 222 22 mmmm m Hmmm n a WM mfl til .1eafl t w w w o m um Oeb FCPEH 67233 55666 99999 11111 64 90 1 00789 96720528 59 00 22333 d n a g n E s e v 0 n 90 n 6 0Q 99 f 11 lln4 ,7 w98 52?- 5l eO4 e DRoo-JD f hm d m N m n e Mme v flm rm AFP ll] 2 7 -I-24 it[ill [73] Assignee Coal Industry (Patents) Limited Primary ExaminerEmest R. Purser London England Altorne Stevens Davis Miller & Mosher 32Priority Aug.6, 1968 Y r [33] Great Britain [54] HARDNESS SENSING ROTARYCUTTERS FOR ABSTRACT: A rotary cutter for a mineral mining machineparticularly a shearer loader or trepanner. The cutter comprises acutter head equipped with fixed cutter tools distributed around thehead. Immediately behind and adjacent one fixed tool there is aresiliently mounted tool which extends in the direction of its lengthslightly beyond the adjacent fixed tool. This ensures a constant shallowpenetration for the resiliently mounted tool during cutting.

00 Mom 2 1m s E m N n I n u H m m m e m m g m n N m I] n NW N n u MD m mL3 m m A m m Rm L L mm c C S L M9 U h H H 299/1 /39, 50 A positionsensitive transducer is mounted in the head to give a signal indicativeof [50] Field ofSearch.......................

movement of the resiliently mounted tool under varying load S T N m M Aa w S m n A w T 8 e D E H N U Q U so that change in mineral hardness ata seam boundary can be detected and the machine steered accordingly.

PATENTED [ED291976 3; 550,959

sum 2 ar 2 FIG. 3

HARDNESS SENSING ROTARY CUTTERS FOR MINERAL MINING MACHINES It is wellknown for a cutter tool to be held in a holder resiliently mounted onthe head of a rotary cutter, and to provide means sensitive to themovement of the holder relative to the head which derive a signalindicative of said movement. With such a cutter the signal derived fromthe means varies according to the type of mineral being cut by the tooland also according to the tool penetration into the mineral.Unfortunately, if the tool penetration is not constant, as is usuallythe case, a varying signal will be derived and a change in the signaldue to a change in the type of mineral being cut by the tool may bemasked.

An object of this invention is to providea rotary cutter which overcomesthe above-mentioned disadvantage.

According to the present invention a rotary cutter for a mineral miningmachine comprises a rotary head, cutter tools fixedly mounted on, anddistributed around, said head, a resilient mounting member mounted onsaid head, a further tool mounted on said resilient mounting member soas to be movable relative to said head, said further tool being sopositioned relative to one of said fixedly mounted tools that thepenetration of said further tool over at least a substantial part of thecutting path of said further tool is shallow and constant, and meansmounted on said head which are sensitive to relative movement betweensaid further tool and said one of said fixedly mounted tools, said meansbeing adapted to derive a signal indicative of said relative movement.

Said further tool is preferably located behind, and adjacent, said onefixedly mounted tool and said further tool preferably extends, in thedirection of its length, beyond said one fixedly mounted tool.

Said one fixedly mounted tool thus acts as a shield tool to cut themajor portion of mineral in front of said further tool which thus has ashallow constant penetration in the mineral over a substantial portionof its cutting path. This enables a very clear indication to be obtainedof the boundary of a mineral seam in a manner suitable for a mineralmining machine to be properly steered by manual adjustment or equallywell by automatic adjustment.

One embodiment of the invention will now be described by way of example,with reference to the accompanying drawings in which:

FIG. 1 is a plan of the end of a shearer-loader machine showing therotary cutter drum;

FIG. 2 is a side elevation of the same end of the machine shown in FIG.1; and

FIG. 3 is a vertical section on an enlarged scale on the line Ill-Ill inFIG. 1.

The drawings show the invention applied to a shearerloader machine 10which can move along the upper flanges of a longwall coalface armoredconveyor 12. The machine I has a rotary cutter which comprises a rotarycutter head in the tom of a drum 14 equipped with a backplate 16 andhelical loading vanes 18.

The drum 14 when ready for use is equipped with fixedly mounted cuttertools 20 each mounted in a mounting box 22. The boxes are secured to theinner side of the backplate 16 and to the rear sides of the vanes 18.The drum 14 rotates in the direction ofthe arrow in FIG. 2.

The drum 14 also has a resiliently mounted tool 26 which is locatedimmediately behind one tool 28 of the fixed tools and which extends, inthe direction of its length, beyond the fixed tool 28. The amount ofextension beyond the fixed tool 28 is the amount shown as X, in theradial sense, in FIG. 2.

The tools 26 and 28 are mounted in a mounting assembly 30 supported onthe backplate 16.

FIG. 3 shows the assembly 30 in more detail. It comprises a housing 32to which is welded a mounting box 22 for the tool 28 and in which therewhich there is a cross-channel 34. The channel 34 accommodates amounting box 36 for the tool 26, which box is secured by bolts 38 to theupper end of a short I section cantilever 40. The lower end of the beam40 is secured by bolts 42 to the housing 32 at the base of the channel34:

The ends and top of the channel 34 areclosed by an inverted U-shapedcover plate 44 held by screws 46. Clearance (not shown) is provided at48 between the inner edge of a cutout 50 in the cover plate and theupper edge of the'mounting box The housing 32 has a cylindrical insert52having a bore 54 to receive an electromagnetic movement transducer 55connected by leads 56 to a control circuit described below. A dirt seal58 surrounds the inner end of the insert 52 and engages the side of thebox 36. There is a smallclearance between the inner end of the inert 52and the box 36.

The housing 32 also has a cylindrical plug 60 slidable in a bore in thehousing which engages the box 36 and is backed by a rubber block 62 andby a cylindrical backing disc 64. A screw 66 adjustable in the housing32 has its inner end engag ing the backing disc 64 and has a locknut 68.

The cantilever beam 40 is resilient and allows the tool 26 to move backrelative to the housing 32 and relative to the drum 14 under cuttingload. Such movement causes inductive changes in the electromagnetic fluxacross the airgap between the transducer in the bore 54 and the box 36,and the transducer produces a corresponding electrical signal for thecontrol circuit.

If the screw 66 is screwed into the housing 32, a preload is applied tothe cantilever beam 40 through the rubber block 62 which is deformed andacts as a spring to apply the preload to the beam 40. This preloadenables the. effective zero-force level at the tip of the tool 26 to bevaried to suit the external electrical circuit. This is, below a certainvalue of force applied to the tip of the tool 26 there is no deflectionof the beam 40 and no signal from the transducer 55 in the bore 54. Thispreload facility is entirely optional in many applications can bedispensed with.

The assembly 30 is readily mounted as a whole on the backplate l6 andcan be removed as a whole for repair or adjustment. The assembly is verycompact and robust. The beam 40 in particular is very short. The boxes22, 36, are very closely positioned so that the tools 28, 26 are asclose as possible.

The close location of the tool 26 behind the tool 28 ensures that thetool 26 has effectively a constant shallow penetration by the amount Xbeyond the penetration of the tool 28. In the case of toolson a drum ofa shear-loader machine there is a very pronounced variation in depth ofpenetration during cutting, the depth varying from zero at the start ofthe cutting and increasing to maximum at the middle of the arc andfalling to zero at the end of the 180 are. This variation would renderany attempt at detecting a seam boundary quite ineffective. However,using the leading tool 28 according to the invention with the tool 26extending slightly beyond the tool 28 the signal obtained from thetransducer can bemade to indicate changes of mineral hardness withsufficient accuracy for indication or control purposes.

By way of example the amount X may be one-half inch where the maximumpenetration of the tool 28 is 2 inches.

In a modification, the first tool 28 may be wider than the tool 26. Thismay be used particularly where the rotary cutter is the cutter head of atrepanner machine.

The inner end of the insert 52 acts as a stop for the box 36, should theforce on the tool 26 become excessive.

The signal from the transducer 55 passes to a receiving and displaycircuit (not shown) which may be positioned in a roadway remote from themachine and which converts the signal into any desired form.

This circuit also comprises further means which related the signal fromthe transducer 55 to the angular position of the tool 26 about the axisof rotation of the drum 14. The further means could comprise threemicroswitches actuated by cams mounted on the cutter head drive shaft.One microswitch is actuated for the time the tool 26 is cutting and thusenables the receiving circuit to determine the amplitude of the averagesignal derived from the transducer 55. By comparing the actual signalderived from the transducer 55 with the average signal it is possible todetermine if any peak signals occur. The invention particularly enablesa very pronounced peak signal to be obtained. If the type of coal beingcut gives rise to a fluctuating signal it may be found beneficial tocompare the actual signal from the transducer with a signal equal to oneand fivetenths times the average signal. Even then, very pronounced peaksignals can be achieved.

Any peak signal which may occur is fed via a Schmitt trigger unit to twoAND gate units arranged in parallel. One of the AND gate units iselectrically connected to the second microswitch which is actuated byits associated cam when the tool 26 is cutting adjacent the roof of theseam. The second AND gate unit is connected with the third microswitchwhich is actuated by its associated cam when the tool 26 is cuttingadjacent the floor of the seam.

Each AND gate unit has, therefore, two inputs which, when suitablymatched, cause a signal to be transmitted from the AND gate unit to adisplay circuit. The display circuit may comprise two pilot lights, oneof which lights up when a signal is transmitted from its associated ANDgate unit.

As the shearer-loader moves along the mineral face, the cutter headmoves towards a boundary of the coal scam, the tool 26 starts to cut thedifferent, usually harder, mineral adjacent the coal seam and a signalis derived from the transducer 55 which causes a signal to betransmitted from oneof the AND gate units as previously described. Thislatter signal is related to the angular position of the tool 26 and thusto the seam boundary at which the hard mineral is being cut and,therefore, indicates what steering action should be applied to correctthe position of the cutter head.

The steering action may be applied manually or automatically, i.e., thesignal is transmitted from the AND gate unit to means arranged toactuate the shearer steering mechanism.

In alternative embodiments, the further means which relate the signal tothe angular position of the tool 26 may comprise a magslip arrangementor a wiper moving around an impedence bridge. With these embodiments thesignal derived from the transducer 55 could be continuously displayed onan oscilloscope having a circular timebase.

Although the specific embodiment is described above in relation to ashearer type of machine, the invention is equally applicable to othertypes of machine, for example a trepanner.

In a modification, the radial pick type of tools shown could be replacedby point-attack type tools for example. Also, in general, theresiliently mounted tool may differ in one or more respects (in additionto length) from the adjacent fixed tool.

I claim:

1. A rotary cutter for a mineral mining machine comprising a rotaryhead, cutter tools fixedly mounted on, and distributed around, saidhead, a resilient mounting member mounted on said head, a further toolmounted on said resilient mounting member so as to be movable relativeto said head, said further tool being so positioned relative to one ofsaid fixedly mounted tools that the penetration of said further toolover at least a substantial part of the cutting path of said furthertool is shallow and constant, and means mounted on said head which aresensitive to relative movement between said further tool and said one ofsaid fixedly mounted tools, said means being adapted to derive a signalindicative of said relative movement.

2. A rotary cutter as claimed in claim 1, in which said further tool islocated behind, and adjacent, said one fixedly mounted tool and in whichsaid further tool extends, in the direction of its length, beyond saidone fixedly mounted tool.

3. A rotary cutter as claimed in claim 2, in which said one fixedlymounted tool is wider than said furthertool.

4. A rotary cutter as claimed inclaim l, in which said rotary head is ahead suitable for a shearer-loader type of mineral mining machine.

5. A rotary cutter as claimed in claim 4, in which said rotary head hasat one end a backplate, and in which said one fixedly mounted tool andsaid further tool are mounted on said backplate.

6. A rotary cutter as claimed in claim 1, in which said rotary head is atrepanning head suitable for a trepanner-type mining machine.

7. A rotary cutter for a shearer-type mineral mining machine comprisinga rotary head, said rotary head having at one end a backplate, cuttertools fixedly mounted on, and distributed around, some of said fixedlymounted tools being mounted on and distributed around said backplate, aresilient mounting member mounted on said backplate, a further toolmounted on said resilient mounting member so as to be movable relativeto said head, said further tool being located behind, and adjacent, oneof said fixedly mounted tools on said backplate and said further toolextending, in the direction of its length, beyond said one fixedlymounted tool on said backplate, and means mounted on said backplatewhich are sensitive to relative movement between said further tool andsaid one fixedly mounted tool on said backplate, said means beingadapted to derive a signal indicative of said relative movement.

8. A rotary cutter for a mineral mining machine, comprising a rotaryhead, cutter tools fixedly mounted on, and distributed around, saidhead, a housing mounted on said head, a first tool-receiving box carriedby said housing in fixed relation thereto, one of said fixedly mountedtools being mounted in said first box, a resilient member carried bysaid housing, a second tool-receiving box carried by said resilientmember, a further tool mounted in said second box so as to be movablerelative to said head, said second box and said further tool beingpositioned behind, and adjacent, said first box and said one fixedlymounted tool, respectively, and said further tool extending, in thedirection of its length, beyond said one fixedly mounted tool, and meansmounted on said housing which are sensitive to relative movement betweensaid further tool and said one fixedly mounted tool, said means beingadapted to derive a signal indicative of said relative movement.

9. A rotary cutter as claimed in claim 8, comprising a preload plugslidably mounted relative to said housing, one end of said plug engagingsaid second box, a resilient element located behind said plug, a disclocated behind said element, and a screw adjustably mounted in screwedrelationship with said housing behind said disc, one end of said screwengaging said disc. I

